Iranian Journal of Materials Science & Engineering http:// ijmse.iust.ac.ir
Iranian Journal of Materials Science and Engineering - Journal articles for year 2010, Volume 7, Number 2Yektaweb Collection - http://www.yektaweb.comen2010/6/11NUMERICAL SIMULATION OF COMBUSTION SYNTHESIS OF ALUMINIDE INTERMETALLIC COMPOUNDShttp://ijmse.iust.ac.ir/browse.php?a_id=254&sid=1&slc_lang=en
<p>Combustion synthesis is a special thermophysico-chemical process applied for production of intermetallic compounds. In the present work, a reaction–diffusion numerical model was developed to analyze the combustion synthesis of aluminide intermetallics by self-propagating high-temperature synthesis process. In order to verify the reliability of the numerical model, an experimental setup was designed and used to perform the combustion synthesis of nickel and titanium aluminides. The developed model was further used to determine the temperature history of a powder mixture compact during self-propagating high-temperature synthesis. The effect of compact relative density on combustion temperature and wave propagation velocity was also studied.</p> M. R. AboutalebiA STUDY ON THE ALUMINIZING OF ELECTRODEPOSITED NICKELAT 500 oChttp://ijmse.iust.ac.ir/browse.php?a_id=255&sid=1&slc_lang=en
<b><font face="TimesNewRomanPS-BoldItalicMT"><font face="TimesNewRomanPS-BoldItalicMT"><p align="left"><font size="2">Abstract: </font></p><p align="left"><font size="2">nanocrystalline nickel samples with the grain size of ~25 nm were prepared via direct current electrodeposition and</font></p><p align="left"><font size="2">aluminized for different durations by pack cementation method at 500 </font></p><p align="left"><font size="2">means of SEM, EDS and XRD techniques. According to results, short time aluminizing resulted in the formation of a</font></p><p align="left"><font size="2">single aluminide layer whereas at long duration two distinct aluminide layers were formed. The growth kinetics of the</font></p><p align="left"><font size="2">coating was non-parabolic at short times while it obeyed the parabolic law at long duration. The parabolic growth</font></p><p align="left"><font size="2">rate constant of single phase coating formed on electrodeposited samples was about 30 ìm / h1/2 approximately 3 times</font></p><p align="left"><font size="2">greater than the data reported for coarse grained nickel (8.4 ìm / h1/2). Meanwhile, the overall growth rate constant</font></p><p align="left"><font size="2">was decreased to 11.7 ìm / h1/2, when double aluminide layers formed on nanocrystalline nickel.</font></p></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">In this research, aluminizing behavior of ultra fine-grained nickel was investigated. For this purpose,</font></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT" size="2">o</font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">C. The aluminide layers were examined by</font></font></font></b> A. AmadehTHE EFFECT OF AGING TREATMENT ON MECHANICAL PROPERTIES OFAA6082 ALLOY: MODELINGAND EXPERIMENThttp://ijmse.iust.ac.ir/browse.php?a_id=256&sid=1&slc_lang=en
<b><font face="TimesNewRomanPS-BoldItalicMT"><font face="TimesNewRomanPS-BoldItalicMT"><p align="left"><font size="2">Abstract: </font></p><p align="left"><font size="2">properties of AA6082 aluminum alloy. Considering that aging phenomenon affects the distribution of alloying element</font></p><p align="left"><font size="2">in matrix, and the fact that different distribution of alloying elements has different impediments to dislocation</font></p><p align="left"><font size="2">movement, a material model based on microstructure, has been developed in this research. A relative volume fraction</font></p><p align="left"><font size="2">or mean radius of precipitations is introduced into the flow stress by using the appropriate relationships. The GA-based</font></p><p align="left"><font size="2">optimization technique is used to evaluate the material constants within the equations from the uni-axial tensile test</font></p><p align="left"><font size="2">data of AA6082 alloy. Finally, using the proposed model with optimized constants, the flow behavior of the alloy at</font></p><p align="left"><font size="2">different conditions of heat treatment is predicted. The results predicted by the model showed a good agreement with</font></p><p align="left"><font size="2">experimental data, indicating the capability of the model in prediction of the material flow behavior after different heat</font></p><p align="left"><font size="2">treatment cycles. Also, the calculated flow stress was used for determination of the material property in Abaqus</font></p><p align="left"><font size="2">Software to analyze the uniaxial compression test. The force- displacement curves of the analysis were compared to</font></p><p align="left"><font size="2">the experimental data obtained in the same condition, and a good agreement was found between the two sets of results.</font></p></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">A novel constitutive equation has been proposed to predict the effect of aging treatment on mechanical</font></font></font></b> Karimi TaheriEVALUATION OF THE MECHANICAL PROPERTIES OF NIOBIUM MODIFIED CAST AISI H 13 HOT WORK TOOL STEELhttp://ijmse.iust.ac.ir/browse.php?a_id=257&sid=1&slc_lang=en
<font face="TimesNewRomanPS-BoldItalicMT"><font face="TimesNewRomanPS-BoldItalicMT"><p align="left"><font size="2">Abstract: </font></p><p align="justify"><font size="2">mechanical properties of AISIH 13 hot-work tool steel have been studied. Cast samples made of the modified new steel </font><font size="2">were homogenized and austenitized at different conditions, followed by tempering at the specified temperature ranges. </font><font size="2">Hardness, red hardness, three point bending test and Charpy impact test were carried out to evaluate the mechanical </font><font size="2">properties together with characterizing the microstructure of the modified steel using scanning electron microscope. </font><font size="2">The results show that niobium addition modifies the cast structure of Nb–alloyed steel, and increases its maximum </font><font size="2">hardness. It was found that bending strength bending strain, impact strength, and red hardness of the modified cast </font><font size="2">steel are also higher than those of the cast H13 steel, and lower than those of the wrought H13 steel. </font></p></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">In this research, the effects of partially replacing of vanadium and molybdenum with niobium on the</font></font></font> Sh. KheirandishEFFECT OF MECHANICAL ACTIVATION ON THE KINETICS OF LEACHINGOFCHALCOPYRITE IN THE FERRIC SULFATE MEDIAhttp://ijmse.iust.ac.ir/browse.php?a_id=258&sid=1&slc_lang=en
<b><font face="TimesNewRomanPS-BoldItalicMT"><font face="TimesNewRomanPS-BoldItalicMT"><p align="left"><font size="2">Abstract: </font></p><p align="left"><font size="2">has been investigated. It has been shown that the mechanism of leaching reaction is diffusion through the product layer</font></p><p align="left"><font size="2">and does not undergo any change as a result of mechanical activation in a wide range of experimental conditions.</font></p><p align="left"><font size="2">Leaching rate is strongly influenced by milling intensity and the effect of ball to powder mass ratio is stronger than</font></p><p align="left"><font size="2">milling time. Curve fitting of experimental data shows that leaching rate constant is approximately a linear function</font></p><p align="left"><font size="2">of ball to powder mass ratio, while it obeys a power function with regard to the milling time.</font></p></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">The kinetics of chalcopyrite leaching in a ferric sulfate media for raw and mechanically activated samples</font></font></font></b> M.Sh. BafghiEFFECT OF FUELS ON THE COMBUSTION SYNTHESIS OF NiAL2O4 SPINEL PARTICLEShttp://ijmse.iust.ac.ir/browse.php?a_id=259&sid=1&slc_lang=en
<b><font face="TimesNewRomanPS-BoldItalicMT"><font face="TimesNewRomanPS-BoldItalicMT"><p align="left"><font size="2">Abstract: </font></p><p align="left"><font size="2">as magnetic materials, semiconductors, pigments, catalysts, refractories and electronic ceramics. In this paper, we</font></p><p align="left"><font size="2">reported the preparation of NiAl</font></p><p align="left"><font size="2">The resulting powder was chracterized by XRD, particle size analysis and SEM. The XRD patterns show that the</font></p><p align="left"><font size="2">combustion technique was excellent to prepare single – phased cubic NiAl</font></p><p align="left"><font size="2">found to be around 14 nm. From the particle size analysis, it was found that the 50 % of the particles lie below 30</font></p><p align="left"><font size="2">µm. The micrographs show the formation of fluffy agglomerates composed of fine particles.</font></p></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">Spinels constitute an advanced group of materials with great technologial appeal, being able to be applied</font></font></font><font size="2"><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT">2</font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT">O</font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT">4 </font></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">spinels by low temperature combustion technique using glycine and urea as fuels.</font></font></font><font size="2"><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT">2</font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT">O</font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT">4 </font></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">particles and the crystallite sizes were</font></font></font></b> A. Samson NesarajSTUDY ON ELECTROWINNING OF COBALT BY CYCLIC VOLTAMMETRYTECHNIQUEhttp://ijmse.iust.ac.ir/browse.php?a_id=260&sid=1&slc_lang=en
<b><font face="TimesNewRomanPS-BoldItalicMT"><font face="TimesNewRomanPS-BoldItalicMT"><p align="left"><font size="2">Abstract: </font></p><p align="left"><font size="2">the competition between the precipitation of cobalt ions and evolution of hydrogen gas on the cathode surface during</font></p><p align="left"><font size="2">the reduction process in a sulfate bath, investigation on the mechanism of metal precipitation is of great importance.</font></p><p align="left"><font size="2">In the present work, study on the kinetics of cobalt electrowinning and the mechanism of the involved reactions have</font></p><p align="left"><font size="2">been carried out. The obtained results, confirm the mechanism of cobalt precipitation by depletion of hydroxides. The</font></p><p align="left"><font size="2">effects of temperature and scan rate parameters were studied on electrowinning of cobalt by cyclic voltammetry</font></p><p align="left"><font size="2">technique. The diffusion coefficient and rate constant of the reactions were measured and calculated by performed</font></p><p align="left"><font size="2">experiments.</font></p></font></font><font face="TimesNewRomanPS-ItalicMT"><font face="TimesNewRomanPS-ItalicMT"><font size="2">Nowadays cobalt is mostly produced through the electrowinning process of sulfate solutions. Regarding to</font></font></font></b> M. Nusheh*